On-chip transformers may be used in radiofrequency integrated circuits (RFICs) for impedance matching, signal coupling and phase splitting. Like traditional transformers, on-chip transformers include a primary winding for the signal input and a secondary winding for the signal output. A varying current in the primary winding creates a varying magnetic flux in the transformer's air core, and thus a varying magnetic flux through the secondary winding. This varying magnetic flux induces a varying electromotive force (EMF), or voltage in the secondary winding. This effect is called inductive coupling. If a load is connected to the secondary winding, current will flow in this winding, and electrical energy will be transferred from the primary circuit through the transformer to the load. Transformers may be used for AC-to-AC conversion of a single power frequency or for conversion of signal power over a wide range of frequencies. For on-chip applications, it is advantageous to reduce the footprint of the transformer while achieving a desirable coupling coefficient.